P1404 – OBD-II DTC

OBD-II DTC P1404 – Glow Plug Circuit High Side

DTC P1404 meaning

DTC P1404 refers to a diagnostic trouble code indicating a problem with the glow plug circuit, specifically a high-side fault. This code is commonly associated with diesel engines that utilize glow plugs to aid in cold starting. The high-side fault suggests that there is an issue with the voltage supply to the glow plug circuit, which may prevent the glow plugs from functioning correctly.

DTC P1404 symptoms

Common symptoms associated with DTC P1404 may include:

• Difficulty starting the engine, especially in cold weather
• Increased engine cranking time
• Rough idling or misfiring during initial startup
• Check Engine Light (CEL) illuminated on the dashboard
• Decreased fuel efficiency

DTC P1404 causes

Several factors can lead to the triggering of DTC P1404, including:

• Faulty glow plugs
• Wiring issues, such as damaged or corroded connectors
• Defective glow plug relay
• Malfunctioning engine control module (ECM)
• Short circuits in the glow plug circuit

DTC P1404 seriousness

The seriousness of DTC P1404 can vary depending on the symptoms experienced. While it may not cause immediate engine damage, it can lead to:

• Increased difficulty in starting the engine
• Potential for further engine performance issues
• Increased emissions due to incomplete combustion

It is advisable to address this code promptly to avoid more significant problems down the line.

How to diagnose DTC P1404

To diagnose DTC P1404, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P1404 code.
2. Inspect the glow plug circuit for visible damage or corrosion.
3. Test the glow plugs for proper resistance using a multimeter.
4. Check the glow plug relay for functionality.
5. Examine the wiring and connectors for shorts or breaks.
6. Verify the voltage supply to the glow plug circuit.
7. Check the ECM for any software updates or faults.

How to fix DTC P1404 step-by-step instructions

To fix DTC P1404, follow these steps:

1. Clear the DTC using an OBD-II scanner.
2. If the code reappears, replace any faulty glow plugs.
3. Repair or replace damaged wiring and connectors in the glow plug circuit.
4. Replace the glow plug relay if it is found to be defective.
5. Reprogram or replace the ECM if necessary.
6. Perform a final check to ensure all connections are secure and components are functioning correctly.

How to erase DTC P1404

To erase DTC P1404, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the ignition without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to clear the trouble codes.
5. Disconnect the scanner and start the engine to check if the code reappears.

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